You had it right and then you sunk deeper and deeper into the "no" lol.
Appendix is the best possible way to carry your firearm when driving. Or in general these days. It's like a modern method that we've noticed has improved speed and defensive retention. And in some cases, doesn't hinder maneuverability. (Bending down to pick up things for one)
The seat belt should be against your belt as your holster's belt loops are. You simply lift the shirt and present your firearm. From this, you can remove the seatbelt with your left hand and proceed to exit the vehicle if need be. Usually, you don't have to. Car > Gun. But we're speaking of a worst-case scenario.
Source: Classes. Everyone teaches something different and everyone thinks that what they teach is gospel. So naturally, you'll go with how you trained. As I'm passing this information onto you. My particular training is from the appendix position in a vehicle and from 3 o'clock. We tried the other methods and it was done in a way that deterred us from ever wanting to use them in real-world applications. Such as ankle or small of back.
Solution: Take a class and train for it. If it smells funny, try another class with an instructor who teaches differently. Not everyone can appendix carry because of weight issues and such. And not everyone can draw their pistol out from behind them for the same reasons. This does not mean getting one of those silly magnets or leaving your gun loose while you drive. Never do that! If you must glove box or center console it, just remember its there. That is the least ideal place to have your gun with you in a vehicle.
So try some classes out.
Hope this helps and didn't trigger anyone. We're all friends here.